As I said in another thread, what I would do here is to have the NX as a unified console, but sell it in 2 different packages.
· Portable-only: A cheaper package, containing the tablet screen/controller and the detachable controls. It would also feature its own cartridge port, so it is capable of executing the games, obviously.
· Desktop experience: Contains all of the above, plus a charging dock for the controller and an extra box that connects to the TV and has its own bigger CPU and GPU, and also its own cartridges slot.
This way, you can have a handheld device that works as a standalone handheld and is a fully portable console on its own, and also a, let's say, PC-like box connected to the TV that will be capable of displaying the handheld games on the TV with better resolution and framerate. On the other hand, the TV box, with its own cartridge slot, would receive its own line of games that require more power to be executed, hence becoming the de facto home console of Nintendo.
This way Nintendo would have a unified platform, but 2 lines of products: the handheld-only games that could also be seen on a TV screen for the audience that's not interested on desktop gaming; and bigger, more resource-needy games that could only be played in the more powerful TV box.